Freezing PC ? sounds like a Harddisk with bad sectors
If your PC is showing symptoms like this:
> - Frequently freezes, on a laptop with 3GB of RAM.
> No informative spinner/hourglass, it just freezes until
> it decides it's finished. Top and system monitor don't
> show anything hogging resources.
Then this cause is usually a harddisk with bad sectors. SMART monitoring and error reporting is poor in both Linux and Windows, and the system behaviour of Linux and Windows has been the same in the past: Freezing for 30 seconds per error.